Log-levelling machines

ABSTRACT

A log-levelling machine having at least one rotary cutter in the shape of a conical disc and a device for advancing logs in their longitudinal direction toward the rotary cutter or cutters. The machine operates to flatten the logs on their lateral sides by cutting the excess material into chips. According to the invention, that portion of each rotary cutter which is located next to the flattened surface of a log which is being cut is provided with a set of teeth adapted to cut chips of substantially smaller thickness than the chips cut by the remaining teeth of the cutter.

United States Patent N ilsson Feb. 29, 1972 [54] LOG-LEVELLIING MACHINES[72] lnventor: Philip Nilsson, Kaptensgatan 3A,

Soderhamn, Sweden [22] Filed: Dec. 19, 1969 21 Appl. No.: 886,496

[30] Foreign Application Priority Data Dec. 20, 1968 Sweden ..17591/68[52] US. Cl ..144/176,144/118,144/3 P [51] Int. Cl ..B27l 11/02, B27c1/08 [58] Field of Search ..144/l76, 162, 326, 3-14,

[56] References Cited UNITED STATES PATENTS Tomlinson "114/176 1 Standal144/162 PHmaryEiaminer-Donald R. Schran AttorneyBrumbaugh, Graves,Donohue & Raymond 57 ABSTRACT A log-levelling machine having at leastone rotary cutter in the shape of a conical disc and a device foradvancing logs in their 7 Claims, 2 Drawing Figures PAIENIEDFEm m2s.s45,30e

INVENTOR fi P Amara/V 5 his A TORNEYS LOG-LEVELLING MACHINES BACKGROUNDOF THE INVENTION The present invention relates to an improvement insocalled log-levelling machines or canters. Such machines provided withat least one and normally two opposed rotary cutters-i.e., cone-shapedcarriers which support chipper teeth or knives-as well as means foradvancing logs in their longitudinal direction into the area between thecutters. The machines operate to make level the logs on two oppositesides by cutting the excess material into pulp chips.

More particularly, the present invention relates to a modification inthe teeth of the above-type rotary cutters to achieve an improvement inthe cut log surface.

Log-levelling machines having rotary carriers in the shape of conicaldiscs have previously been proposed. Thus, one machine is known whichhas two opposed discs designed as truncated cones, the narrower ends ofwhich face each other and carry sawblades projecting outside theenvelope surfaces of the conical discs. The sawblades operateessentially as ordinary circular sawblades and the material which islocated outside of the blades and cut from the log is cut into chipsafter the sawing operation by knives on the rotary carriers. This typeof machine has the disadvantages that it produces a considerablequantity of sawdust and that the chips obtained are not of satisfactoryquality.

According to another proposal, two opposed conical rotary discs areprovided to serve as tool carriers. Attached to the carriers areseparate cutters disposed circumferentially in a spiral and axially in ahelix. Each cutter has one edge cutting substantially in a planecontaining the grain of the logs at the point of contact and anotheredge at an angle thereto which cuts transversely to the grain. Inpractice, the cutting operation is generally called parallel chipping.

Log-levelling machines of this kind operate satisfactorily with theexception of one minor drawback which is particularly marked if the woodis very knotty. This drawback arises from the fact that, next to thesurface to be levelled, cutters will at times work against the grain andmay thereby tear out parts of the log surface leaving the surface rough.In practice, this problem is not very serious but for certain types ofwood, it would be desirable to avoid it.

SUMMARY OF THE INVENTION An object of the present invention, therefore,is to find a way of improving log-levelling machines of the typedescribed above so as to eliminate the log tearing problem and leave asmooth flat surface.

This object, as well as other objects which will become apparent in thediscussion which follows, is achieved, according to the presentinvention, by providing the rotary carriers, on the portion thereofwhich is located next to the flattened surface of a log, with specialcutter teeth or knives for cutting chips of substantially smallerthickness than the chips cut by the other knives of the rotary carriers.

It has been found that the special set of cutter teeth or knives,according to the invention, act to smooth the rough wood surfaceproduced by the remainder of the cutting teeth without additionallytearing material away from the surface of the log.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of arotary cutter or cutting disc having special teeth according to thepresent invention.

FIG. 2 is a diagrammatical top view of a log-levelling machine employingtwo opposed rotary cutters of the type shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments ofthe present invention will now be described with reference to FIGS. 1and 2 of the draw- The log-levelling machine to which the presentinvention relates, shown only diagrammatically in FIG. 2, comprises aframe (not shown) in which two cutting discs 10 and 11 are rotatablyjoumaled and driven by a motor (not shown). The discs 10 and 11 have theshape of truncated cones and have their narrower ends facing each other.Further, the discs carry a plurality of cutters 12 which will bediscussed in detail below. The discs 10 and 11, which may be adjustablein direction towards and away from each other, are each adapted to workon one side of a log 13 advanced in a longitudinal direction between thediscs. The means for advancing the log. indicated generally at 20,includes rollers 21, 22 supporting the log. The log is thus made levelon two opposed sides by cutting up the excess material into pulp chips.

The log-levelling machine according to the invention is suitable forlevelling two opposed sides of a round log and also a log alreadylevelled on two sides so that a square log is obtained. The latter, infact, is what is shown in FIG. 2.

FIG. 1 shows that, in this example, the conical disc is provided with anumber of cutters disposed in a spiral circumferentially and a helix inthe axial direction. In the disc that is shown each cutter has a mainedge 14 adapted to operate in the same plane as the grain of the log atthe point of contact and an edge 15 adjoining the main edge andoperating in a plane transverse to the grain. However, it should bestressed that the improvement according to the present invention is notlimited to this type of cutter configuration and may also be used in thecase of conical cutting discs having elongated knives extendingsubstantially in parallel to the envelope surface of the disc.

According to the present invention, the part of each cutting disc 10, 11located next to the level surface of the log-i.e., in the present casethe flat narrow end of the conical discis provided with a set of cutters16 which are adapted to cut chips substantially smaller than theremainder of the chips, especially as regards their thickness.

It is possible to achieve the desired cutting function just mentioned ina number of different ways. In each separate case it is only required,according to the general principle, that the chips out next to the levelsurface of the log are relatively thin so that the cutting forces becomeslight and thus also those forces become slight which might otherwisecause large bits to be torn out of the log surface. However,particularly advantageous results seem to be obtainable, according to apreferred embodiment of the present invention, iffor the purpose statedcutters are used which consist of the cutters known per se having a mainedge extending in the same plane as the grain of the log at the point ofcontact and an edge adjoining the main edge and extending in a planeintersecting the grain. These cutters are preferably arranged in acircular row with the main edges located in the same planeperpendicularly to the axis of rotation of the disc in question.

Further, it is convenient according to the present invention to providethe cutters of the particular set, such as the cutters 16, on a separateholder. In the present example this holder is in the form of an annulardisc 17 which is preferably readily replaceable and disengagably securedto the central portion of the conical disc.

As illustrated particularly clearly in FIG. 1, the surface of theannular disc 17 facing the log is provided with annular ribs 19 withintermediate grooves 18. Inter alia, said ribs have the purpose ofcontributing to the guidance of the log while keeping low the frictionagainst the flat log surface.

The ribs 19 and annular grooves 18 have also another important function.Sometimes it is desirable to bring the cutting discs 10, 11 tightlytogether to cut an entire log of inferior quality into pulp chips. Insuch cases, if the discs were quite smooth on the end surfaces thereofwhich face each other, it might be difficult to bring them entirelytogether. If, instead, the discs exhibit the ribs 19 and grooves 18,staggered in relation to each other on the two discs so that when thediscs are brought tightly together there is formed an arrangementresembling a labyrinth seal, no slot can be formed between the discs.

For the same reason, the special sets of cutters 16 on the cutting discs10, 11 may be disposed on the same radius but circumferentiallystaggered on the two discs. With this latter arrangement, however, thediscs should be driven synchronously, preferably by the same driveshaft.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes, andadaptations, and that the same are intended to 'be comprehended withinthe meaning and range of equivalents of the appended claims.

I claim:

1. in a log-levelling machine including (a) at least one rotary carrierin the shape of a conical disc having first cutter means arranged on theconical surface of the disc, and (b) means for advancing logs in theirlongitudinal direction to place a lateral side thereof in contact withsaid at least one rotary carrier thereby to make the log flat on saidlateral side by cutting the excess material on said lateral side intochips, the improvement wherein a portion of said at least one carrierwhich is located next to the flattened surface of a log is provided withsecond cutter means for cutting chips substantially smaller than thechips cut by said first cutter means, said second cutter means includinga plurality of cutters arranged in a circular row, each of said cuttershaving a main edge disposed on a common plane and extending in the sameplane as the grain of the log at the point of contact with the log andhaving an edge adjoining the main edge extending in a plane intersectingthe grain.

2. In a log-levelling machine including (a) at least one rotary carrierin the shape of a conical disc having first cutter means arranged on theconical surface of the disc, and (b) means for advancing logs in theirlongitudinal direction to place a lateral side thereof in contact withsaid at least one rotary carrier thereby to make the log flat on saidlateral side by cutting the excess material on said lateral side intochips, the improvement wherein a portion of said at least one carrierwhich is located next to the flattened surface to a log is provided withsecond cutter means for cutting chips substantially smaller than thechips cut by said first cutter means, said second cutter means includinga plurality of cutters and holder means, to which each of said cuttersis secured, and which is disengagably secured to the central portion ofsaid rotary carrier, whereby said second cutter means is readilyreplaceable.

3. The improvement defined in claim 2, wherein said holder means is anannular disc.

4. The improvement defined in claim 3, wherein the surface of saidannular disc facing the log has annular ribs with intermediate grooves.

5. The improvement defined in claim 4, wherein said loglevelling machineincludes two rotary carriers arranged in opposite relationship; whereinsaid log-advancing means is adapted to advance logs in theirlongitudinal direction between said opposite rotary carriers and whereinsaid annular ribs and grooves on said the two annular discs of said tworotary carriers are staggered such that the ribs of one of said discsare located axially opposite the grooves of the other disc.

6. The improvement defined in clam 5, wherein said two rotary carriersare driven synchronously.

7. The improvement defined in claim 6, wherein the cutters of one ofsaid discs are circumferentially staggered in relation to the cutters ofthe other disc so that the discs may be brought tightly together withoutthe cutters forming an obstacle.

1. In a log-levelling machine including (a) at least one rotary carrierin the shape of a conical disc having first cutter means arranged on theconical surface of the disc, and (b) means for advancing logs in theirlongitudinal direction to place a lateral side thereof in contact withsaid at least one rotary carrier thereby to make the log flat on saidlateral side by cutting the excess material on said lateral side intochips, the improvement wherein a portion of said at least one carrierwhich is located next to the flattened surface of a log is provided withsecond cutter means for cutting chips substantially smaller than thechips cut by said first cutter means, said second cutter means includinga plurality of cutters arranged in a circular row, each of said cuttershaving a main edge disposed on a common plane and extending in the sameplane as the grain of the log at the point of contact with the log andhaving an edge adjoining the main edge extending in a plane intersectingthe grain.
 2. In a log-levelling machine including (a) at least onerotary carrier in the shape of a conical disc having first cutter meansarranged on the conical surface of the disc, and (b) means for advancinglogs in their longitudinal direction to place a lateral side thereof incontact with said at least one rotary carrier thereby to make the logflat on said lateral side by cutting the excess material on said lateralside into chips, the improvement wherein a portion of said at least onecarrier which is located next to the flattened surface to a log isprovided with second cutter means for cutting chips substantiallysmaller than the chips cut by said first cutter means, said secondcutter means including a plurality of cutters and holder means, to whicheach of said cutters is secured, and which is disengagably secured tothe central portion of said rotary carrier, whereby said second cuttermeans is readily replaceable.
 3. The improvement defined in claim 2,wherein said holder means is an annular disc.
 4. The improvement definedin claim 3, wherein the surface of said annular disc facing the log hasannular ribs with intermediate grooves.
 5. The improvement defined inclaim 4, wherein said log-levelling machine includes two rotary carriersarranged in opposite relationship; wherein said log-advancing means isadapted To advance logs in their longitudinal direction between saidopposite rotary carriers and wherein said annular ribs and grooves onsaid the two annular discs of said two rotary carriers are staggeredsuch that the ribs of one of said discs are located axially opposite thegrooves of the other disc.
 6. The improvement defined in clam 5, whereinsaid two rotary carriers are driven synchronously.
 7. The improvementdefined in claim 6, wherein the cutters of one of said discs arecircumferentially staggered in relation to the cutters of the other discso that the discs may be brought tightly together without the cuttersforming an obstacle.